1. Field of the Invention
The present invention relates to protective head gear, namely a helmet, wherein the helmet distributes a localized impact force across a much larger area relative to area of impact.
2. Background of the Prior Art
The combat helmet is a type of personal protection worn by a soldier during combat. It is one of the oldest forms of personal armor, having been known to be worn by the Assyrians as far back as 900 BC. The modern helmet is typically formed as an outer shell made from a ballistic material such as Kevlar or Aramid. These materials offer excellent bullet and fragmentation stopping power although most helmets are unable to stop a direct hit from a high caliber high velocity round. Although the ballistic outer shell may save the soldier's life, severe injury may occur when a bullet or shrapnel hits the helmet causing the wearer traumatic brain injury. Such traumatic brain injuries may have drastic and long-term negative effects on the sufferer. The reason for such injuries is that ballistic materials are designed to prevent penetration of an incoming round or fragment and not necessarily for energy dissipation. So while the helmet prevents the bullet or fragment from directly contacting and penetrating the user's head, the incoming round or fragment has a tremendous amount of kinetic energy that is absorbed by the outer shell and transferred to the user's head resulting in a localized and often severe injury to the head at the area of impact.
To address this problem, many helmets have an inner layer that is made from a cushioning material such as high density closed cell foam. This cushioning layer is designed to absorb the energy absorbed by the outer shell due to impact from a bullet or fragmentation. This cushioning layer also protects the user from non-ballistic assaults onto the wearer's head such as concussive shockwaves and even vehicle accidents. While such a cushioning layer helps reduce the injury caused from a bullet or fragment impact with the outer shell, the potential for serious injury remains due to the fact that the cushioning layer can dissipate only a certain amount of energy for a given amount of cushioning material. As the helmet must be supported by the neck muscles, the helmet must be relatively light weight so that the soldier can wear the helmet for extended periods of time without undue discomfort. Modern military helmets are designed to be less than four pounds, so the helmet designer must make tradeoffs between the amount of ballistic material to be used versus the amount of cushioning material to be used. Additionally, some weight must be devoted to add brackets that hold various items such as night vision goggles, nape armor to protect the lower head and neck, camouflage coverings, etc. All these requirements make the design of a modern helmet one of tradeoffs and compromises. An additional factor that needs to be considered in helmet design is heat. A helmet traps body heat about the head of the wearer, especially in desert combat situation as has been seen in the last two decades or so. Such heat can dramatically diminish the cognitive functioning of the solder and thus his or her combat effectiveness. As foam tends to be a good heat trap, the helmet designer needs to take this fact into consideration when designing and budgeting for the cushioning layer.
What is needed is a helmet that has ballistic properties so that many bullets and shrapnel fragments are stopped by the helmet yet helps prevent traumatic brain injury as a result of such stoppage and also reduces injury from explosive shock waves such those from nearby explosions. Such a helmet must be able to effectively diffuse the absorbed kinetic energy introduced by the stopped round or fragment allowing the energy to be dissipated over a relatively large area of the user's head. By minimizing the localization of energy absorption by the head, the potential for serious traumatic brain injury at the impact site is significantly lessened. Such a helmet must meet the current requirements for combat helmets by being relatively lightweight and by helping minimize head overheating by the soldier.